Vacuum centrifuge

ABSTRACT

To permit centrifuging in a high vacuum, an airtight housing has a centrifuge container located therein, mounted on a shaft to rotate at high speed. Within the airtight housing, a plurality of turbine rotor rings are located, connected to the shaft, the space between the turbine rings having interdigited turbine stator rings mounted thereon, so that, upon rotation of the centrifuge, the rotor and stator rings will cooperate to provide a high vacuum in the region of the centrifuging container.

atent 1 VACUUM CENTRIFUGE Inventor: Max Wutz, Wilhelmsbaden Ring 6,

Hanau-Hohe Tanne, Germany Filed: Feb. 25, 1972 Appl. No.: 229,489

Foreign Application Priority Data Mar. 19, 1971 Germany 2113460 US. C1 233/16, 233/24, 233/1 A Int. Cl 1304b 15/08 Field of Search 233/1 R, l A, 11, 23 R,

References Cited UNITED STATES PATENTS 5/1945 Peer 233/23 R 451 July 9, 1974 3,108,955 10/1963 Boyland 233/24 X 3,304,990 2/1967 Ontko et 211....

3,327,938 6/1967 Stallmann 233/24 X Primary ExaminerGeorge H. Krizmanich Attorney, Agent, or FirmF1ynn & Frishauf ABSTRACT To permit centrifuging in a high vacuum, an airtight housing has a centrifuge container located therein, mounted on a shaft to rotate at high speed. Within the airtight housing, a plurality of turbine rotor rings are located, connected to the shaft, the space between the turbine rings having interdigited turbine stator rings mounted thereon, so that, upon rotation of the centrifuge, the rotor and stator rings will cooperate to provide a high vacuum in the region of the centrifuging container.

10 Ciaims, 2 Drawing Figures 1 VACUUM CENTRIIFUGE The present invention relates to a high vacuum centrifuge and more particularly to an ultracentrifuge to operate within an evacuated housing.

Centrifuges have been proposed which, during centrifuging, operate essentially in a vacuum. To obtain the vacuum, it was customary to use diffusion vacuum pumps. Diffusion vacuum pumps require a comparatively substantial warm-up time, so that they are not immediately operable, and centrifuging under vacuum must be delayed from the time that the centrifuge and vacuum apparatus are actually started. Diffusion pumps of this type, additionally, frequently are operated with oil which requires special provisions to keep the housing within which the rotor is mounted free from oil vapors.

It is an object of the present invention to provide a centrifuge, and more particularly an ultra-high speed centrifuge which can be operated within a vacuum, which is compact and immediately available for use.

SUBJECT MATTER OF THE PRESENT INVENTION a trifuge operates.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a highly schematic side view of one embodiment of the present invention; and

FIG. 2 is a highly schematic similar side view, illustrating another embodiment, similar parts in the two embodiments having been given similar reference numerals.

The centrifuge of FIG. 1 is located within a housing (1), which can be evacuated. The rotor, or centrifuging container 2 sits on a shaft 4, the container 2 being standard and having the form of any centrifuge as desired. The housing 1 is formed with a flanged evacuation stub 3 to form an exhaust port, to which a pump P can be connected, the pump P being an exhaust pump of simple design to provide an initial low pressure within housing 1. Shaft 4 is suitably journaled on its top side adjacent'the centrifuging container 2, as well known in the art and only schematically indicated. The lower end of shaft 4 is carried through the housing by means of a vacuum seal 5a, and then directly connected to a drive motor 6. The drive motor may be a hysteresis, or other asynchronous motor, a split-cylinder motor, a shaded pole motor or the like.

In accordance with the invention, and located within the airtight housing 1, subject to evacuation through stub 3, are turbine rotor blade rows 7 to form the turbine rotors of a turbo-molecular vacuum pump. These rings 7 are axially spaced from each other. Stator turbine guide rings, containing guide blades, or director blades 8, are secured to the inner wall of the housing 1, and arranged to fit'between the axial spaces of the rotor turbine rings 7. The rows 7, and the stator blades 8 are preferably essentially disk-shaped, the disks of the rotor and stator being located in interfitting, interdigited arrangements.

Upon rotation of shaft 4, suction will be created by the combined action of the rotor rings 7 and the stator rings 8, in a downward direction with respect to FIG. 1, the uppermost rotor rings 7 providing a suction zone, so that the vacuum created is highest in the region in which the container 2 is located.

The upper ring 7 itself forms the suction opening, the arrangement being so made that the drive motor 6 is located below the bottom-most rotor blade 7.

'In the arrangement in accordance with FIG. 1, the turbomolecular vacuum pump, formed by the rotor and stator rings 7 and 8 respectively, provides a high vacuum in the region of the container 2. The blades of the rotor rings and of the stator rings are similar to those of an axial compressor, by itself well known in the art.

The embodiment of FIG. 2 is similar to that of FIG. 1 except that the drive is different. Instead of the vacuum bushing 5a as in FIG. 1, shaft 4 terminates within the housing 1 and is journaled in a thrust bearing 5b. The rotor blades 7, as before, are secured to the shaft 4. The shaft 4 at the bottom, however, carries a rotor 6a of an electric motor having a stator 6b located outside of the housing, so that the housing need not be pierced by a shaft seal, which introduces leakage. In this type of drive, a hysteresis motor is particularly useful, the rotor of which is disk-shaped, rotating with respect to stator winding. Different types of drive motors, for example, asynchronous motors, are also useful.

Various changes and modifications can be made within the inventive concept, particularly with respect to the drive and the actual construction of the turbomolecular vacuum pump. When the present invention is used with ultra-high speed centrifuges operable in a vacuum, the rotating turbine rings are driven directly from the motor, thus providing the desired high speed.

Hysteresis motors can be controlled particularly simply and accurately by means of electrical and electronic speed control. They have the advantage to operate asynchronously upon starting, and, when reaching nominal speed, having essentially the characteristics of a synchronous motor. The arrangement of providing a high molecular pump on the same shaft as the drive of a centrifuge provides a compact, simple ultra-speed centrifuge which can operate without special oil or lubrication and which is immediately operable upon connection to an electrical drive, with or without (but preferably with) additional vacuum exhausts through pump P. For reference with respect to the motors, any motor handbook or, for example, the Standard Handbook for Electrical Engineers (McGraw Hill Book Co., Inc., New York, Toronto, London) may be consulted.

The combination of motor and rotor container within the housing has the additional advantage that the vacuum increases as the centrifuging speed increases,,that is, as the speed of the motor increases, since both the rotor of the pumpas well as the centrifuging container are operated from the same shaft. No special arrangements to keep out oil vapors, as in diffusion pumps, are necessary.

The specific type of vacuum molecular pump utilized in the present invention, and shown only schematically,

is well known in the art and described for example in U.S. Pats. No. 3,168,977 and 3,168,978.

1 claim:

1. Vacuum centrifuge comprising an airtight housing (1) and an exhaust port (3) formed in the housing;

a shaft (4) extending into the housing;

a centrifuging container (2) to hold the substance to be centrifuged connected to the shaft;

a motor (6) drivingly connected to the shaft;

a plurality of turbine rotor rings (7) spaced axially from each other on the shaft to rotate therewith; and

a plurality of turbine stator rings (8) located within the housing and interengaging in the spaces between the turbine rotor rings, the turbine rotor rings and the turbine stator rings together forming a turbo-molecular vacuum pump entirely located within the housing, to evacuate the housing as the centrifuging container is rotated by the motor, and create a vacuum adjacent said centrifuging con tainer.

2. Vacuum centrifuge according to claim 1, wherein the centrifuging container (2) is located on the shaft above the turbine rotor rings (7).

3. Vacuum centrifuge according to claim 1, wherein the drive motor (6) is located below the turbine rotor rings (7).

4. Vacuum centrifuge according to claim 1, wherein the drive motor is directly connected with the shaft.

5. Vacuum centrifuge according to claim 1, wherein the turbine rotor rings, the shaft and the drive motor form a unitary assembly.

6. Vacuum centrifuge according to claim 1, wherein the drive motor is a hysteresis or asynchronous motor.

7. Vacuum centrifuge according to claim 1, including a thrust bearing (6) located in the housing, the shaft being journaled in the thrust bearing and entirely contained within the housing.

8. Vacuum centrifuge according to claim 7, wherein the motor has a rotor and a stator and the rotor of the motor is connected to the shaft within the housing, the stator being located outside of the housing.

9. Vacuum centrifuge according to claim 1, including a rotary vacuum seal (5a) through the housing, the shaft passing through the vacuum seal in airtight manner;

the motor being located outside of the housing.

10. Vacuum centrifuge according to claim 1, including an external vacuum pump (P) connected to the exhaust port (3).

CERTIFIEAT F COR Patent No. 3,822,823 mama July 9, 1974 Inventor s) x UTZ It is certified that error appears in the above-identified patent v and that said Letters Patent are hereby corrected as shown below:

Assignee; Heraeus-Christ GmbI-I Osterode, Germany Signed and sealed this 26th day of November 1974*,

(SEAL) Atteet:

@coY M. cmssom JR. Attotimg @fficer C. MALL DANN Coiseioner of Pafiemze USCOMM-DC 60376-P69 i U. 5. GOVERNMENT PRINTING OFFICE 1 I969 0-366-334.

F ORM PO-IOSO (IO-69) 

1. Vacuum centrifuge comprising an airtight housing (1) and an exhaust port (3) formed in the housing; a shaft (4) extending into the housing; a centrifuging container (2) to hold the substance to be centrifuged connected to the shaft; a motor (6) drivingly connected to the shaft; a plurality of turbine rotor rings (7) spaced axially from each other on the shaft to rotate therewith; and a plurality of turbine stator rings (8) located within the housing and interengaging in the spaces between the turbine rotor rings, the turbine rotor rings and the turbine stator rings together forming a turbo-molecular vacuum pump entirely located within the housing, to evacuate the housing as the centrifuging container is rotated by the motor, and create a vacuum adjacent said centrifuging container.
 2. Vacuum centrifuge according to claim 1, wherein the centrifuging container (2) is located on the shaft above the turbine rotor rings (7).
 3. Vacuum centrifuge according to claim 1, wherein the drive motor (6) is located below the turbine rotor rings (7).
 4. Vacuum centrifuge according to claim 1, wherein the drive motor is directly connected with the shaft.
 5. Vacuum centrifuge according to claim 1, wherein the turbine rotor rings, the shaft and the drive motor form a unitary assembly.
 6. Vacuum centrifuge according to claim 1, wherein the drive motor is a hysteresis or asynchronous motor.
 7. Vacuum centrifuge according to claim 1, including a thrust bearing (6) located in the housing, the shaft being journaled in the thrust bearing and entirely contained within the housing.
 8. Vacuum centrifuge according to claim 7, wherein the motor has a rotor and a stator and the rotor of the motor is connected to the shaft within the housing, the stator being located outside of the housing.
 9. Vacuum centrifuge according to claim 1, including a rotary vacuum seal (5a) through the housing, the shaft passing through the vacuum seal in airtight manner; the motor being located outside of the housing.
 10. Vacuum centrifuge according to claim 1, including an external vacuum pump (P) connected to the exhaust port (3). 